As everyone has mentioned there is a lot that can change this answer.
Assuming you have a good connection with no splitting and at least 1/3 of the screw embedded:
#6 screw: 50lbs shear, 150lbs pullout
#8 screw: 60lbs shear, 180lbs pullout
#10 screw: 80lbs shear, 210lbs pullout
MKDesign 